This invention relates to a vehicular windshield wiper crank assembly and more particularly to a novel method and joint assembly for joining the crank plate to the wiper pivot shaft. The prior art is replete with arrangements in general for connecting stud members and the like to a metal plate which typically rely in some fashion on an interference fit between the members to provide a secure joint. Typically, a stud member includes a spline or knurled portion which is pressed into a corresponding opening formed in a plate member having a softer material than the stud. The knurled portion may be provided with a tapered leading end which is driven into the opening in the plate or alternately, a chamfered opening is provided in the plate and the stud is forced into the opening at the chamfer position. As the stud member is forced therein, the softer material in the plate flows around the splines or knurled portion of the stud member. To assure permanence of the connection, heat may be applied causing the material to melt and flow into the splined areas of the shaft. Often, it is necessary to subject the assembly to heat treatment to attain the necessary hardness of the plate material. If the connection is to be subjected to rotary and axial torques, it is further necessary to provide additional material for welding or staking the shaft to the plate.
With regards to windshield wiper crank assemblies, the wiper blade pivot shaft and crank plate are comprised of metal or steel of similar hardness. Formation of the subject joint in this environment will cause shearing of the post knurls rather than a positive deformity causing a tight interference such that the joint will not withstand specified torque tests. Thus, the prior art relating to windshield wiper crank assemblies have joined the pivot post to the crank plate by staking, welding shrinkage, or expansion fits, hot upset and like processes which generally are time consuming, expensive procedures and which must be held to extremely close tolerances.